The present invention relates to the development of microlithographic resists on the surfaces of semiconductor wafers and more particularly to a variable time method of development.
While it has previously been known to observe or monitor the development of wafer resist in batch processes, e.g., utilizing a laser illuminating a wafer surface through a window in a batch development tank, such procedures have not been available for the spin development of wafers which is the currently preferred method of development in actual production manufacture.
Among the objects of the present invention are the provision of automatic process control for the development of exposed resist on the surface of semiconductor wafers; the provision of such a method which is applicable to spin development of semiconductor wafers; the provision of such a method which provides variable time development; the provision of such a method which prevents over- or under-development; the provision of such a method which optically monitors the progress of the development; the provision of such a method which is highly reliable and which may be implemented by equipment and procedures which are relatively simple and inexpensive. Other objects and features will be in part apparent and in part pointed out hereinafter.